In recent years, a movement has gained traction to replace incandescent light bulbs with lighting fixtures that employ more efficient lighting technologies, as well as to replace relatively efficient fluorescent lighting fixtures with lighting technologies that produce a more pleasing, natural light. One such technology that shows tremendous promise employs light emitting diodes (LEDs). Compared with incandescent bulbs, LED-based light fixtures are much more efficient at converting electrical energy into light, are longer lasting, and are also capable of producing light that is very natural. Compared with fluorescent lighting, LED-based fixtures are also very efficient, but are capable of producing light that is much more natural and more capable of accurately rendering colors. As a result, lighting fixtures that employ LED technologies are replacing incandescent and fluorescent bulbs in residential, commercial, and industrial applications.
Unlike incandescent bulbs that operate by subjecting a filament to a desired current, LED-based lighting fixtures require electronics to drive one or more LEDs. The electronics generally include a power supply and special control circuitry to provide uniquely configured signals that are required to drive the one or more LEDs in a desired fashion. The presence of the control circuitry adds a potentially significant level of intelligence to the lighting fixtures that can be leveraged to employ various types of lighting control. Such lighting control may be based on various environmental conditions, such as ambient light, occupancy, temperature, color temperature, and the like. For example, daylighting is a control technique that is used to regulate the light output levels of one or more lighting fixtures based on ambient light levels.
Light in a particular area may come from various sources. For instance, the area may have a group of lighting fixtures as well as supplemental light sources from which supplemental light is received at different levels throughout the day. The supplemental light sources may be natural, artificial, or a combination thereof. Ambient light is considered the combination of the light provided by the group of lighting fixtures and the supplemental light provided by the supplemental light sources.
Daylighting generally refers to the process of dynamically regulating the output level of the light emitted by the lighting fixtures, based on the ambient light level for the area to maintain a desired ambient light level for the area. As the amount of supplemental light increases, the group of lighting fixtures will decrease their light output levels in a proportionate manner to maintain a desired ambient light level. Similarly, as the amount of supplemental light decreases, the group of lighting fixtures will increase their light output levels.